The reason that you cant install the operating system on a RAID is because an incompatibility issue of USB Floppies Drives and the operating system.
This issue affect to both Windows XP and Server 2003 - This is a Microsoft issue not a hardware issue.
The quickest and easiest way to install the operating system on a RAID is slipstreaming the drivers into the installation CD. This utility is Free to download
And some guidance from Intel Web site.